The present invention relates to the sterilization and disinfection arts. It finds particular application in conjunction with the evaluation of the concentration of peracetic acid in a sterilization or disinfection system obtained from a single use package of a concentrated decontaminant composition and will be described with particular reference thereto. It should be appreciated, however, that the invention is also applicable to other liquid sterilization and disinfection processes where the sterilant or disinfectant is effective above a minimum effective concentration, such as liquid hydrogen peroxide or sodium hypochlorite sterilization or disinfection systems.
Disinfection connotes the absence of pathogenic life forms. Sterilization connotes the absence of all life forms, whether pathogenic or not. The term decontamination is used herein to connote sterilization, disinfection or other antimicrobial treatments.
Until recently, medical equipment and instruments were often decontaminated in a steam autoclave. Autoclaves kill life forms with a combination of high temperature and pressure. However, steam autoclaves have several drawbacks. The high temperature pressure vessels are often bulky and heavy. The high temperature and pressure tend to curtail the useful life of endoscopes, rubber and plastic devices, lenses, and portions of devices made of polymeric materials and the like. Moreover, a typical autoclave decontaminating and cool down cycle is sufficiently long that multiple sets of the medical instruments are commonly required.
Liquid decontamination systems have been developed for equipment which could not withstand the high temperatures of steam decontamination. Commonly, a technician mixes a liquid disinfectant composition immediately prior to use and manually immerses the items to be decontaminated. The high degree of manual labor introduces numerous uncontrolled and unreported variables into the process. There are quality assurance problems with the weakening of the decontaminant chemicals due to aging on the shelf, and technician errors in the mixing of decontaminant, control of immersion times, rinsing of residue, exposure to the ambient atmosphere after the rinsing step, and the like. On occasion, powdered reagents are carried away from the mixing region and deposited in undesired locations before they dissolve or react. When such systems are used for decontaminating medical instruments, undissolved reagent particles remaining on the medical instruments after a decontamination process are considered undesirable.
Recently, integrated decontamination systems, such as peracetic acid decontamination systems, have been developed which provide a premeasured dose of a decontaminant in solution. Items to be sterilized are inserted into a receiving tray of a sterilization system and a cartridge of concentrated decontaminant inserted into a well. As water flows through the system, the decontaminant is diluted and carried to the receiving tray. At the end of a decontamination cycle, the decontaminant solution is disposed of and a fresh cartridge of the concentrated decontaminant inserted into the system for the next cycle.
U.S. Pat. No. 5,662,866 to Siegel, et al. discloses a two-compartment cup for use in such a system, which holds powdered sterilant reagent components. An outer cup holds a first reagent while an inner cup, disposed within the outer cup, holds a second reagent. Peripheral walls of inner and outer cups are affixed together at their open ends at flanges. A permeable sheet is affixed to the inner cup portion flange for sealing both cups and for allowing venting of gases from the inner cup during storage. The outer cup is closed at its base by a first detachable base and the inner cup is similarly closed by a second detachable base. In use, the two bases are opened to allow mixing of the two reagents. The two-compartment cup provides a reproducible, pre-measured dose of reagents, while also facilitating handling and shipping of the reagents.
It is trusted that the decontamination system will be at or above the minimum effective concentration of the decontaminant for a predetermined period, so that effective decontamination is obtained. However, differences in ambient temperature, the quantity of items to be disinfected or sterilized and the level of contamination on the items can, nevertheless, lead to variations in how well the decontaminant concentration is maintained over the period of the decontamination cycle. In addition, storage conditions sometimes lead to degradation of peracetic acid precursors before use. Other factors, such as poor instrument cleaning or water quality may also affect decontaminant concentration. For medical instruments in particular, therefore, an additional assurance of satisfactory peracetic acid concentration is desired.
Dippable, chemically-treated papers are available for checking that the peracetic acid concentration in the sterilization system reached a minimum acceptable level for sterilizing or disinfecting. A chemically-treated paper strip is typically inserted into the decontamination system and evaluated at the end of the cycle for a color change, or other indication that the level of the decontaminant has been satisfactory. However, such strips are often omitted from the sterilization system, lost, or remain in the system for several cycles, and thus they are not a reliable record of whether the correct level of decontaminant was obtained in each cycle.
The present invention provides for a new and improved decontaminant package and indicator system and method of use which overcomes the above-referenced drawbacks and others.
In accordance with one aspect of the present invention, a single-use package for holding and selectively releasing a powdered composition is provided. The composition forms a solution of an anti-microbial decontaminant when mixed with water. The package includes a porous portion which is impermeable to the powdered composition but is permeable to water and to the solution. An indicator on the porous portion exhibits a detectable change on exposure to the decontaminant in the solution.
In accordance with another aspect of the present invention, a package for releasing an antimicrobial composition into a flowing liquid is provided. The package includes a side wall having a first opening at a first end and a second opening at a second end such that the liquid flows through the first opening into the package and out through the second opening. A layer of porous material spans one of the first and second openings such that the liquid flows through the porous material layer. An antimicrobial source is disposed within the package for releasing the antimicrobial composition into the flowing liquid to form an antimicrobial solution. An indicator on the porous material layer changes color in response to contact with the antimicrobial solution. The degree of color change varies in accordance with (i) the concentration of an antimicrobial agent in the solution contacting the indicator, and (ii) the duration that the solution contacts the indicator. The degree of color change of the indicator is indicative of duration of contact and the concentration of the antimicrobial agent in the contacting solution.
In accordance with yet another aspect of the present invention, a method includes flowing water through a cartridge containing a composition to form a decontaminant solution from the composition and the water. The cartridge includes a porous region impregnated with an indicator. The indicator exhibiting a detectable change when contacted with a decontaminant solution for a period of time and at a concentration of a decontaminant in the solution sufficient to effect decontamination of items. The method further includes circulating the decontaminant solution in a fluid flow path comprising a microbial decontamination chamber, in which the items to be decontaminated are positioned, and the porous region, and examining the indicator for the detectable change.
One advantage of the present invention is that it provides a rapid method of indicating that adequate levels of a decontaminant in a decontamination cycle were maintained.
Another advantage of the present invention is that it ensures that the level of decontaminant is evaluated in every decontamination cycle.
Yet another advantage of the present invention is that it provides a record of decontaminant levels which may be stored with other records of the decontamination cycle.
A further advantage of the present invention is that it provides a clear yes-or-no indication of whether a minimum effective concentration of peracetic acid was present during the entire cycle.
Still further advantages of the present invention will become apparent to those of ordinary skill in the art upon reading and understanding the following detailed description of the preferred embodiments.